地下工程支护-结构一体管幕预筑法技术及发展

Technology and Development of Support-Structure Integral Pipe-roofing Pre-construction Method for Underground Works

地下工程支护-结构一体管幕预筑法:,是一种全新的暗挖施工方法,其核心思想不同于传统地下工程暗挖法,即首先施作地铁车站永久结构,然后在永久结构保护下进行全断面土方开挖。支护-结构一体管幕预注法的施工关键技术包括大直径钢管长距离顶进施工技术、管幕空间切割焊接成形技术及狭小空间钢筋混凝土结构施工技术。通过实践证明,该技术将加固、支护、主体结构合为一体并一次建造成形,可大大减少开挖支护步序,降低临时支撑用量:,有效控制地层变形,保证地下良好的作业环境。

The construction-induced upfloating of shield tunnel on South Changsha Railway Station-Guangda Station Section of Changsha Metro Line No.4 needs to be rehabilitated.As a result,the replacing technology of defective shield tunnel segment by composite lining is proposed according to the environment and geological conditions.(1)After route fitting by measured data,the defective shield tunnel length is about 40 m,and segment should be replaced reaches 25(from ring 223 to 247).(2)The replacing technology of defective shield tunnel segment by composite lining is the best choice according comparison results among different replacing technologies by fuzzy comprehensive evaluation method.(3)The displacement and stress variation of ground and segment is studied by finite element method when dismantling ring by ring;and the results show bad situations,i.e.,increase of vertical displacement crown top of surrounding rock,connected plastic zones of crown top of surrounding rock,increase of vertical displacement toward tunnel inside and horizontal displacement toward tunnel outside at segment adjacent to ring 1,compression of segment and increase of bending moment and axial force of segment,etc;which indicates that the segment dismantling number should be strictly controlled.(4)A new kind of movable trolley and its relevant construction technologies are developed and put into application to guarantee the safety of the tunnel structure and rapid construction.